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        // 圆周率
        console.log(Math.PI);
        // 向上取整
        console.log(Math.ceil(3.14));
        // 向下取整
        console.log(Math.floor(3.14));
        // 四舍五入
        console.log(Math.round(3.14));
        // 随机数
        console.log(Math.random());
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